The great leaps forward in industrial technology and continual development of multimedia products have enabled tremendous satisfaction of our senses of sight and hearing. In particular, many music companies nowadays have launched online music services that allow users to listen to music and songs directly through the Internet without having to buy CDs or vinyl records. As listening to music with earphones incurs compression, and hence discomfort, of the ears and keeps the listener from lying on one side of the body or making large movements at will, a desirable alternative is to play music through a stereo system, whose loudspeaker quality is also far superior to that of earphones and therefore ensures better enjoyment of music.
Generally, a stereo system designed to make the most of acoustic resonance to create a satisfactory sound field has a loudspeaker mounted in a loudspeaker box. The cavity in the box serves as a resonance chamber, which amplifies the sound output from the loudspeaker. Referring to FIG. 1, a conventional loudspeaker box L includes a hollow housing L1, a loudspeaker L2, and a cover L3. The hollow housing L1 is provided with an opening L11 at the front side and a receiving space L12 in its interior. The receiving space L12 is in communication with the opening L11 in order to receive a sound source control circuit L13. The loudspeaker L2 is mounted to the cover L3 and is electrically connected to the sound source control circuit L13 in order for the membrane of the loudspeaker L2 to vibrate according to audio signals transmitted from the sound source control circuit L13 and thereby produce the corresponding sound effects. The cover L3 is mounted to the hollow housing L1 to cover the opening L11. When the membrane of the loudspeaker L2 applies a rearward pushing force to the air in the hollow housing L1 by instantaneous vibrations, the hollow housing L1 resonates at a low frequency.
Since stereo systems can be used for different purposes and in different places (e.g., in the living room of a residence, in an outdoor plaza, at a concert venue, on an athletic field, etc.), people's requirements of such systems are not exactly the same, and in light of this, structural improvements have been made to loudspeaker boxes to meet user needs. The applicant of the present invention has found that the existing loudspeaker boxes can be roughly divided into two major categories: household loudspeaker boxes, whose range of sound projection is relatively small, and those for use with public address (PA) loudspeakers, which feature relatively far sound projection; and that a loudspeaker box that takes into account both near-field and far-field sound effects has yet to be developed. For example, a PA loudspeaker will produce an undesirable sound effect to those who are close to it (i.e., in the near field). After all, the placement of a loudspeaker box requires various spatial acoustic conditions to be considered. The issue to be addressed by the present invention, therefore, is to design a novel loudspeaker box structure configured for both the near and far fields in order to provide users with a better listening experience.